1. Field of the Invention
The present invention relates generally to a center bearing supporting device for supporting a center bearing which rotatably supports a connecting section of a plural-piece propeller shaft, and more particularly to such a center bearing supporting device adapted to effectively suppress the axial and radial vibrations of the propeller shaft.
2. Description of the Prior Art
It is well known that a longer propeller shaft consists of, for example, two pieces connected with each other, in which the joint section of the two pieces is rotatably supported by a center bearing. It is necessary for the center bearing to be elastically connected to a vehicle body in order to prevent axial and radial vibrations of the propeller shaft from being transmitted to the vehicle body. For this purpose, a center bearing supporting device has been proposed as disclosed, for example, in Japanese Utility Model Provisional (First) Publication No. 55-168428, in which an elastic member is securely interposed between an inner tube fitting around the periphery of a center bearing and an outer tube installed to a vehicle body. Additionally lip sections extend from the elastic member toward the axial direction of the propeller shaft. In such a center bearing supporting device, a larger axial relative displacement can be permitted between the inner and outer tubes. Additionally, a larger radial relative displacement is necessary between the inner and outer tubes, thereby enlarging the joint angle change of the propeller shaft joint section. This will increase the vibration exciting force of the propeller shaft.
In order to suppress the radial relative displacement between the inner and outer tubes, another center bearing supporting device has been proposed as disclosed in Japanese Utility Model Provisional (First) Publication No. 58-90831, in which an annular elastic stopper is provided to a device like the above-discussed one in a manner to bridge the inner and outer tubes. However, with this center bearing supporting device, the elastic stopper unavoidably serves to restrict the axial relative displacement between the inner and outer tubes, thereby making insufficient interruption of the axial vibration of the propeller shaft to the vehicle body.